# Latest

**URL:** https://discourse.julialang.org/latest.md?page=965

[Latest](https://discourse.julialang.org/latest.md) · [Categories](https://discourse.julialang.org/categories.md) · [Tags](https://discourse.julialang.org/tags.md)

**Page:** 966

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## [Symbolics.jl | Lie series expansion for PDEs](https://discourse.julialang.org/t/symbolics-jl-lie-series-expansion-for-pdes/84885)

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**Author:** [@Audrius-St](https://discourse.julialang.org/u/Audrius-St)\
**Replies:** 2\
**Last updated:** [August 1, 2022, 7:43pm UTC](https://discourse.julialang.org/t/symbolics-jl-lie-series-expansion-for-pdes/84885 "2022-08-01T19:43:31Z")

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Hello, I’ve used Sympy for several years now and am interested in giving Symbolics.jl a go with an eye to switching over completely. I’ve previously used Sympy to solve systems of ODES using the symbolic Lie series met…

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## [Euler Equation Iteration to solve an Optimization problem](https://discourse.julialang.org/t/euler-equation-iteration-to-solve-an-optimization-problem/84135)

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**Author:** [@Albert\_Zevelev](https://discourse.julialang.org/u/Albert_Zevelev)\
**Replies:** 21\
**Last updated:** [August 1, 2022, 7:20pm UTC](https://discourse.julialang.org/t/euler-equation-iteration-to-solve-an-optimization-problem/84135 "2022-08-01T19:20:11Z")

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I would like to solve a simple/routine economics problem with Euler Equation Iteration. The following code works well: using Interpolations, Plots, LinearAlgebra # PolyBasis(K) = \[ones(size(K)) K K.^2\] PolyGetCoef…

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## [Improve code that estimates parameters using max likelihood, optim, differential equations and automatic differentiation?](https://discourse.julialang.org/t/improve-code-that-estimates-parameters-using-max-likelihood-optim-differential-equations-and-automatic-differentiation/84883)

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**Author:** [@laurar1891](https://discourse.julialang.org/u/laurar1891)\
**Replies:** 7\
**Last updated:** [August 1, 2022, 7:10pm UTC](https://discourse.julialang.org/t/improve-code-that-estimates-parameters-using-max-likelihood-optim-differential-equations-and-automatic-differentiation/84883 "2022-08-01T19:10:26Z")

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I’m trying to find parameters for a model that is in a differential equation form. I created three series of data, and I want the starting point of the differential equation for each series to be an additional parameter …

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## [Time-independent Usage for MOLFiniteDifference()](https://discourse.julialang.org/t/time-independent-usage-for-molfinitedifference/75132)

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**Author:** [@Fathya.Salih](https://discourse.julialang.org/u/Fathya.Salih)\
**Replies:** 5\
**Last updated:** [August 1, 2022, 6:57pm UTC](https://discourse.julialang.org/t/time-independent-usage-for-molfinitedifference/75132 "2022-08-01T18:57:36Z")

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Hello, I am trying to use MOLFiniteDifference() to solve a stationary PDE. In the documentation, it says that the continuous or time variable is optional, but I couldn’t find any examples of someone using it for a stead…

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## [How to find the first time step (column 1) when the values between time steps in column 2 is of a certain difference](https://discourse.julialang.org/t/how-to-find-the-first-time-step-column-1-when-the-values-between-time-steps-in-column-2-is-of-a-certain-difference/85102)

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**Author:** [@HelgavonLichtenstein](https://discourse.julialang.org/u/HelgavonLichtenstein)\
**Replies:** 15\
**Last updated:** [August 1, 2022, 6:36pm UTC](https://discourse.julialang.org/t/how-to-find-the-first-time-step-column-1-when-the-values-between-time-steps-in-column-2-is-of-a-certain-difference/85102 "2022-08-01T18:36:45Z")

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Hello, I would like to know how to select the first time step (in column 1) where the difference between values in column 2 is 0.01. df = DataFrame(x=\[0.0, 0.5, 1.0, 1.5, 2.0\], y=\[0.74, 0.64, 0.84, 0.88, 0.89\]) The a…

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## [Plots.jl contour line colors](https://discourse.julialang.org/t/plots-jl-contour-line-colors/85084)

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**Author:** [@gideonsimpson](https://discourse.julialang.org/u/gideonsimpson)\
**Replies:** 3\
**Last updated:** [August 1, 2022, 6:40pm UTC](https://discourse.julialang.org/t/plots-jl-contour-line-colors/85084 "2022-08-01T18:40:09Z")

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When using contour (not contourf) with Plots.jl, is there a way to force all the contour lines to be a single fixed color?

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## [Translating a 1d convolution from Python to Julia](https://discourse.julialang.org/t/translating-a-1d-convolution-from-python-to-julia/85080)

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**Author:** [@Christopher\_Fisher](https://discourse.julialang.org/u/Christopher_Fisher)\
**Replies:** 6\
**Last updated:** [August 1, 2022, 6:35pm UTC](https://discourse.julialang.org/t/translating-a-1d-convolution-from-python-to-julia/85080 "2022-08-01T18:35:25Z")

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Hi all, I am trying to port some code written in Python. It performs a 1d convolution on a 3d array. The Python and Julia code output arrays with different dimensions and values. Does anyone know the equivalent code on …

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## [Preallocating Vectors of NamedTuples](https://discourse.julialang.org/t/preallocating-vectors-of-namedtuples/85105)

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**Author:** [@mrVeng](https://discourse.julialang.org/u/mrVeng)\
**Replies:** 3\
**Last updated:** [August 1, 2022, 5:44pm UTC](https://discourse.julialang.org/t/preallocating-vectors-of-namedtuples/85105 "2022-08-01T17:44:19Z")

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Dear all, I hope you are well! I have a question regarding preallocating Vectors of NamedTuples. I have a custom struct that contains a field that is a NamedTuple. mutable struct MyCustomStruct{T\<:NamedTuple} param…

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## [Constant propagation vs generated functions](https://discourse.julialang.org/t/constant-propagation-vs-generated-functions/83788)

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**Author:** [@cscherrer](https://discourse.julialang.org/u/cscherrer)\
**Replies:** 26\
**Last updated:** [August 1, 2022, 5:30pm UTC](https://discourse.julialang.org/t/constant-propagation-vs-generated-functions/83788 "2022-08-01T17:30:18Z")

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Before getting started in Julia, I did most of my work in Haskell. It’s a great language, but a few things kept causing me trouble: The strong PL focus of the community was great, but it seemed to come at a cost of con…

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## [Flux.Conv kernel definition](https://discourse.julialang.org/t/flux-conv-kernel-definition/85109)

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**Author:** [@cirobr](https://discourse.julialang.org/u/cirobr)\
**Replies:** 0\
**Last updated:** [August 1, 2022, 5:10pm UTC](https://discourse.julialang.org/t/flux-conv-kernel-definition/85109 "2022-08-01T17:10:14Z")

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Consider the below command line, which defines kernel size as 5x5 and has seven output channels: layer1 = Flux.Conv((5,5), 3 =\> 7, relu; bias = false) Questions: Which kernel(s), given that there are seven output c…

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## [Sunday Small challenge](https://discourse.julialang.org/t/sunday-small-challenge/85041)

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**Author:** [@miguelraz](https://discourse.julialang.org/u/miguelraz)\
**Replies:** 10\
**Last updated:** [August 1, 2022, 4:57pm UTC](https://discourse.julialang.org/t/sunday-small-challenge/85041 "2022-08-01T16:57:20Z")

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Hello Julians! Welcome to the first Sunday Small challenge. I will post 3 lil’ problems - whoever can solve them in Julia (in serial, all architectures allowed) on the input(s) repeated 1000x wins all the internet poin…

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## [Modelling uncertainty propagation in forecasts 🔮](https://discourse.julialang.org/t/modelling-uncertainty-propagation-in-forecasts/85089)

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**Author:** [@agucova](https://discourse.julialang.org/u/agucova)\
**Replies:** 1\
**Last updated:** [August 1, 2022, 2:58pm UTC](https://discourse.julialang.org/t/modelling-uncertainty-propagation-in-forecasts/85089 "2022-08-01T14:58:21Z")

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Hi everyone, I’ve been playing with Causal, a business modeling platform which does automatic uncertainty calculations in forecasts. This works by allowing one to set model parameters in terms of ranges, which are real…

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## [Compiling 1.7.3 on Ubuntu 22.04 stalls](https://discourse.julialang.org/t/compiling-1-7-3-on-ubuntu-22-04-stalls/85070)

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**Author:** [@unhandyandy](https://discourse.julialang.org/u/unhandyandy)\
**Replies:** 12\
**Last updated:** [August 1, 2022, 2:52pm UTC](https://discourse.julialang.org/t/compiling-1-7-3-on-ubuntu-22-04-stalls/85070 "2022-08-01T14:52:08Z")

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I have pulled the git repo and I’m trying to compile v1.7.3, but the process stalls here: Sysimage built. Summary: Total ─────── 53.120629 seconds Base: ─────── 22.231496 seconds 41.851% Stdlibs: ──── 30.887624 seco…

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## [Too many Julia versions?](https://discourse.julialang.org/t/too-many-julia-versions/84538)

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**Author:** [@PetrKryslUCSD](https://discourse.julialang.org/u/PetrKryslUCSD)\
**Replies:** 17\
**Last updated:** [August 1, 2022, 1:53pm UTC](https://discourse.julialang.org/t/too-many-julia-versions/84538 "2022-08-01T13:53:40Z")

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We often hear in this forum that the man power working on Julia is limited. Why then do we have 1.6, 1.7, 1.8, and 1.9 being worked on at the same time? Too many balls in the air…?

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## [Kriging on surface of sphere](https://discourse.julialang.org/t/kriging-on-surface-of-sphere/85058)

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**Author:** [@yakir12](https://discourse.julialang.org/u/yakir12)\
**Replies:** 5\
**Last updated:** [August 1, 2022, 1:47pm UTC](https://discourse.julialang.org/t/kriging-on-surface-of-sphere/85058 "2022-08-01T13:47:39Z")

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I have a few random points on a sphere’s surface and I’d like to interpolate and extrapolate those using kriging. But I’m getting artefacts in the result that look like an issue with the fact that the coordinates are sph…

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## [Porting fragment code Python to Julia](https://discourse.julialang.org/t/porting-fragment-code-python-to-julia/85099)

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**Author:** [@Sergey\_Novak](https://discourse.julialang.org/u/Sergey_Novak)\
**Replies:** 11\
**Last updated:** [August 1, 2022, 12:47pm UTC](https://discourse.julialang.org/t/porting-fragment-code-python-to-julia/85099 "2022-08-01T12:47:41Z")

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selection = np.linspace(0,3,5000000) eps = 0.9 # spikes numpy 1d array ee\_counter = np.array( \[ ( ( spikes \>= selection\[j\] ) & ( spikes \< selection\[j\]+eps ) ).sum() for j in range( len( selection ) ) \] ) pdf = ee\_cou…

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## [ForwardDiff package: no method for expm](https://discourse.julialang.org/t/forwarddiff-package-no-method-for-expm/5759)

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**Author:** [@depasquale](https://discourse.julialang.org/u/depasquale)\
**Replies:** 1\
**Last updated:** [August 1, 2022, 12:25pm UTC](https://discourse.julialang.org/t/forwarddiff-package-no-method-for-expm/5759 "2022-08-01T12:25:14Z")

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Looking to use the ForwardDiff package on code that uses Julias’ matrix exponential, expm, but getting method errors. I guess expm uses some non-native Julia code. Does anyone have any insight here, or a workaround? Any …

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## [Predator-Prey Plot error: no method matching mapslices](https://discourse.julialang.org/t/predator-prey-plot-error-no-method-matching-mapslices/85098)

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**Author:** [@Freya\_the\_Goddess](https://discourse.julialang.org/u/Freya_the_Goddess)\
**Replies:** 1\
**Last updated:** [August 1, 2022, 11:01am UTC](https://discourse.julialang.org/t/predator-prey-plot-error-no-method-matching-mapslices/85098 "2022-08-01T11:01:21Z")

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Hi all, I have this code, Here are what I have done: I change the linspace to range but then error occurs and I do not know how to solve this: I change the backend from pyplot() to gr() MethodError: no method matchin…

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## [Vector to lists of indices grouped by key](https://discourse.julialang.org/t/vector-to-lists-of-indices-grouped-by-key/85050)

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**Author:** [@FireCrumb](https://discourse.julialang.org/u/FireCrumb)\
**Replies:** 9\
**Last updated:** [August 1, 2022, 11:00am UTC](https://discourse.julialang.org/t/vector-to-lists-of-indices-grouped-by-key/85050 "2022-08-01T11:00:46Z")

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Hi, I have a vector of numbers: (in reality much larger) arr = Vector{Int64}(\[6, 9, 9, 4, 1, 1, 2, 7, 8, 3\]) I want to be able to generate the list of indices for each value: \> p = pairs(arr) pairs(::Vector{Int64})(.…

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## [𝐏𝐨𝐬𝐭𝐝𝐨𝐜: 𝐀𝐩𝐩𝐥𝐲𝐢𝐧𝐠 𝐌𝐋/𝐀𝐈 𝐭𝐨 𝐡𝐢𝐠𝐡-𝐝𝐢𝐦𝐞𝐧𝐬𝐢𝐨𝐧𝐚𝐥 𝐛𝐢𝐨𝐦𝐞𝐝𝐢𝐜𝐚𝐥 𝐝𝐚𝐭𝐚 (Julia preferred/Python)](https://discourse.julialang.org/t/julia-preferred-python/85097)

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**Author:** [@Sebastian\_Vollmer](https://discourse.julialang.org/u/Sebastian_Vollmer)\
**Replies:** 0\
**Last updated:** [August 1, 2022, 10:39am UTC](https://discourse.julialang.org/t/julia-preferred-python/85097 "2022-08-01T10:39:55Z")

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Are you looking for a postdoc position that bridges AI and clinical research? Would you like to work between institutions to work on an impactful project with highly granular cohort data? Do you have a background or inte…

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## [Better Cryptography and Blockchain Support](https://discourse.julialang.org/t/better-cryptography-and-blockchain-support/85043)

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**Author:** [@Joe\_Schnetzler](https://discourse.julialang.org/u/Joe_Schnetzler)\
**Replies:** 6\
**Last updated:** [August 1, 2022, 8:55am UTC](https://discourse.julialang.org/t/better-cryptography-and-blockchain-support/85043 "2022-08-01T08:55:02Z")

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Hello all! Founder of Defund Finance (https://defund.app/) and Calypso here. I am a huge Julia user but tend to always be in Goland, Rust, or Nodejs when developing for my blockchain companies. There is a lot of use case…

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## [Pluto interactive bars using GitHub pages](https://discourse.julialang.org/t/pluto-interactive-bars-using-github-pages/85071)

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**Author:** [@RayleighLord](https://discourse.julialang.org/u/RayleighLord)\
**Replies:** 2\
**Last updated:** [August 1, 2022, 8:34am UTC](https://discourse.julialang.org/t/pluto-interactive-bars-using-github-pages/85071 "2022-08-01T08:34:33Z")

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Hello, I recently came across the template repository which allows you to create a webpage in a similar style to the MIT Computational Thinking Course. However, as it stands right now, the notebooks are only shown stat…

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## [\[ANN\] StaticWebPages.jl: A black-box generator for static websites oriented toward academics and personal web-pages](https://discourse.julialang.org/t/ann-staticwebpages-jl-a-black-box-generator-for-static-websites-oriented-toward-academics-and-personal-web-pages/43027)

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**Author:** [@Azzaare](https://discourse.julialang.org/u/Azzaare)\
**Replies:** 8\
**Last updated:** [August 1, 2022, 7:23am UTC](https://discourse.julialang.org/t/ann-staticwebpages-jl-a-black-box-generator-for-static-websites-oriented-toward-academics-and-personal-web-pages/43027 "2022-08-01T07:23:55Z")

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Hi there, I am happy to announce the first beta release of StaticWebPages.jl, a black-box generator for static websites oriented toward academics and personal web-pages. Almost no knowledge of Julia is required, and no…

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## [Package Entanglement: Why using one package breaks another?](https://discourse.julialang.org/t/package-entanglement-why-using-one-package-breaks-another/85079)

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**Author:** [@bogdankjastrzebski](https://discourse.julialang.org/u/bogdankjastrzebski)\
**Replies:** 2\
**Last updated:** [August 1, 2022, 7:20am UTC](https://discourse.julialang.org/t/package-entanglement-why-using-one-package-breaks-another/85079 "2022-08-01T07:20:03Z")

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Hi! I stumped upon an unexpected problem with overall package/library management in julia, that I think is interesting to talk about, because I think it is quite general, and I haven’t found a similar topic. My env: (…

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## [Makie.jl figure with broken axis](https://discourse.julialang.org/t/makie-jl-figure-with-broken-axis/85062)

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**Author:** [@Kevin\_Kleinbeck](https://discourse.julialang.org/u/Kevin_Kleinbeck)\
**Replies:** 3\
**Last updated:** [August 1, 2022, 7:09am UTC](https://discourse.julialang.org/t/makie-jl-figure-with-broken-axis/85062 "2022-08-01T07:09:05Z")

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I intend to create a figure with a broken Axis, which can be useful when the data range is relatively large but relevant details occur only close to the maximal / minimal values. For example, let’s say we want to create…

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## [GPU performance and switching from tabular to recurrent data format for Flux.jl](https://discourse.julialang.org/t/gpu-performance-and-switching-from-tabular-to-recurrent-data-format-for-flux-jl/84969)

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**Author:** [@JLDC](https://discourse.julialang.org/u/JLDC)\
**Replies:** 5\
**Last updated:** [August 1, 2022, 6:52am UTC](https://discourse.julialang.org/t/gpu-performance-and-switching-from-tabular-to-recurrent-data-format-for-flux-jl/84969 "2022-08-01T06:52:48Z")

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When training a recurrent network using Flux.jl, a dataset with K features, S samples, and a sequence length of L should take the form of a vector of length L where each element is a K × S matrix. Let’s say that I have …

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## [Ensemble simulations with random initial conditions that sum to a fixed value](https://discourse.julialang.org/t/ensemble-simulations-with-random-initial-conditions-that-sum-to-a-fixed-value/84951)

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**Author:** [@Dragolonth](https://discourse.julialang.org/u/Dragolonth)\
**Replies:** 6\
**Last updated:** [August 1, 2022, 6:51am UTC](https://discourse.julialang.org/t/ensemble-simulations-with-random-initial-conditions-that-sum-to-a-fixed-value/84951 "2022-08-01T06:51:59Z")

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Hi all. For my ensemble problem, I would like to randomize the initial conditions for each trajectory. However, I would like the sum of certain species to remain a fixed number. For example, if u0 is my set of initial co…

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## [External polynomial supply to DifferentialEquation.jl](https://discourse.julialang.org/t/external-polynomial-supply-to-differentialequation-jl/84906)

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**Author:** [@aasgher385](https://discourse.julialang.org/u/aasgher385)\
**Replies:** 4\
**Last updated:** [August 1, 2022, 6:50am UTC](https://discourse.julialang.org/t/external-polynomial-supply-to-differentialequation-jl/84906 "2022-08-01T06:50:08Z")

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Hi everyone I have a problem solving the Riccati type differential equation. \\frac{dU}{dt} = \\delta \\frac{dD}{dt} - \\lambda U - \\gamma U^2 I have an array of dimension M for D from which, in my opinion we can get …

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## [Basic Performance Difference Between 1.8.0-rc3 and 1.7.2](https://discourse.julialang.org/t/basic-performance-difference-between-1-8-0-rc3-and-1-7-2/85074)

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**Author:** [@Ian\_Slagle](https://discourse.julialang.org/u/Ian_Slagle)\
**Replies:** 2\
**Last updated:** [August 1, 2022, 6:20am UTC](https://discourse.julialang.org/t/basic-performance-difference-between-1-8-0-rc3-and-1-7-2/85074 "2022-08-01T06:20:42Z")

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I have both 1.8.0-rc3 and 1.7.2 installed. I am running the simple benchmark using BenchmarkTools; @benchmark a + b setup=(b = rand(Int64); a = rand(Int64)) which from my understanding, should really just be measuring …

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## [BifurcationKit MethodError](https://discourse.julialang.org/t/bifurcationkit-methoderror/84904)

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**Author:** [@Dragolonth](https://discourse.julialang.org/u/Dragolonth)\
**Replies:** 3\
**Last updated:** [August 1, 2022, 6:14am UTC](https://discourse.julialang.org/t/bifurcationkit-methoderror/84904 "2022-08-01T06:14:37Z")

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Hi all. Currently, I have a reaction network defined in Catalyst, and I’ve been following the tutorial at Bifurcation Diagrams · Catalyst.jl. However, I’ve been running into an error and am not entirely sure how to resol…

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